This invention relates to alkali metal carbonate supported elemental alkali metal catalysts. It is known in the art to prepare an alkali metal carbonate catalyst support by making a thick paste and eventually forming a pelletized, tabletted, and/or granular support. It is also known in the art to use an alkali metal carbonate to support an elemental alkali metal to form a catalyst system useful to promote olefin dimerization. However, these types of catalysts and catalyst supports can suffer from low selectivity for the desired reaction product(s). Thus, it can be difficult to process and obtain economically useful amounts of the reaction product(s) that are desired.